As will be realized, on numerous occasions a police officer has to determine whether or not a suspected material contains a prohibited drug and thus quickly establish probable cause.
Often, the laboratory is closed, or many miles away, and he has no way of making this determination. A test kit can help an officer detect the presence of such drugs of abuse.
The quickest test known for drug identification is a color test in which the response of the drugs to a specific reagent makes it possible to assign the drug to one or more classes.
In order to obtain sufficient evidence to detain a suspected drug peddler or drug user, chemical spot test kits have been commercially developed and are used by many law enforcement agencies for the identification of narcotics and drugs of abuse.
Most of the commercial test kits for the presumptive identification of cocaine are based on contacting cocaine and its salts with cobalt thiocyanate solutions which results in the formation of a relatively water insoluble turquoise complex.
The relative simplicity of the cobalt thiocyanate test made its use feasible outside the laboratory and created a demand for a variation with increased specificity.
The standard Scott Test (L. J. Scott, Specific Field Test for Cocaine, Microgram, VI, 179(1973), is based on the use of cobalt thiocycanate as incorporated in a commercial test kit which contains the chemicals required to perform the test in a prefilled, hermetically sealed glass ampules.
There are three glass ampules:
(1) Cobalt thiocycanate reagent in a 1:1 water glycerine solution; PA0 (2) Concentrated hydrochloric acid; and PA0 (3) chloroform PA0 (1) Remove the plastic clip from the test pack and open the pouch. PA0 (2) Place the suspect cocaine into the pouch, tap or jar the test package, making sure most of this falls to the bottom of the pack. PA0 (3) Refold the pouch at the original fold point and replace the clip securely, sealing the package. PA0 (4) The cobalt thiocyanate ampule should then be broken, releasing the reagent to mix with the suspect material. This can be accomplished by squeezing the center with the thumb and forefinger. When breaking the ampule, the fingers are pushing against smooth glass walls. If the ampule is squeezed at the extreme top or bottom, it could conceivably break through the plastic pouch. Therefore apply even pressure at the center of the ampule. No attempt should be made to crush the small glass particles after the ampule is broken. PA0 (5) With the suspect material in the test package and the reagent released, gently shake or agitate. PA0 (6) If turquoise blue precipitate is formed the second and the third ampules should be broken. PA0 (7) Before discarding the test pack, remove clip and add one measure of acid neutralizer. PA0 (8) Reseal test packs with clips and discard in a tamper-free disposal unit. PA0 (1) Complicated procedure; PA0 (2) It uses corrosive concentrated hydrochloric acid; and PA0 (3) Trace amount of cocaine cannot be detected. PA0 (1) It is economical in that only about 0.2 ml is enough for one test. PA0 (2) It is simple to operate. PA0 (3) Because the solution is not poisonous it can be used for testing large suspected areas. (This advantage cannot be accomplished by ampules). PA0 (4) Trace amounts can readily be detected and distinct turquoise colored spots appear on the surface of the suspect surface even with a short gentle spraying of a quick light coat of reagent. PA0 (1) The propellents are immiscible with the solution and thus two phases are formed. PA0 (2) The solution is relased from the spray as foam that makes the test impossible. PA0 A. Using cobalt thiocyanate reagent in a 1:1 water:gylcerine solution that forms the characteristic blue precipitate with cocaine. In this stage, there are still four drugs that will react with the same color reaction as cocaine: PA0 (1) Phencyclidine (PCP); PA0 (2) Dibucaine; PA0 (3) Butacaine; PA0 (4) Methapyrilene. PA0 B. Addition of concentrated hydrochloric acid to form a clear pink solution. PA0 C. Addition of chloroform which turns blue as the complexed cocaine is partitioned into the organic phase.
The glass ampules are placed into a pouch. The pouch is folded at the top, and a clip is placed over the fold which seals the package.
The following is the recommended test procedure when using this kit:
This method has several disadvantages:
Despite this known disadvantage, in the last ten years no one has proposed or commercialized an improved test kit which would ameliorate these problems.